Process for desulfurizing hydrocarbons with a mixture of ferric and chromic oxides



Patented Jan. 1, 1952 s'lrrr.

PROCESS FOR DESULFURIZING HYDRO- CARBONS WITH A MIXTURE F FERRIC AND CHROMIC OXIDES I Alan C. Abeel, JrL, Roselle, and Henry Hilts l man, Plainfield, N. J., assignors to Standard Oil Development Company, a co'rporatlon of Delaware 1 No Drawing. Application November 26, 1949.

Serial No. 129,698

This invention relates to a process for desulfurizing petroleum hydrocarbons.

In the refining of petroleum and its fractions, the presence of sulfur and sulfur compounds is universally recognized as undesirable. The presence of such sulfur is detrimental from the standpoints of corrosion, odor and, with gasoline fractions, in particular, the octane susceptibility toward lead tetraethyl. Furthermore, the sulfur content of feed stocks to catalytic cracking units also must be kept at a low value in order to avoid adversely affecting the catalyst.

Conventional desulfurization methods may be broadly considered as falling into three classes: (1) sweetening in which mercaptan sulfur is converted into unobnoxious compounds; (2) those processes other than sweetening which are carried out in -the absence of hydrogen such as bauxite desulfurization; (3) and those which are carried out in the presence of hydrogen. Sweetening processes are disadvantageous in that they affect only mercaptan sulfur which in some cases is only converted to a less undesirable form. Bauxite desulfurization and other processes carried out in the absence of hydrogen do not affect refractory sulfur compounds, such as thiophene and its homologs. Those processes usin hydrogen are expensive due to the high cost of hydrogen manufacture and compression.

On the other hand, .the present invention affords a relatively cheap and simple method of removing all types of sulfur from petroleum. According to the present invention the sulfur content of petroleum and any of its fractions is reduced to a desirably low value by contacting the petroleum or its fractions with a coprecipitated mixture of ferric nad chromic oxides in the proportion of about two parts of ferric oxide to one part of chromic oxide. The resulting mixture 1 Claim. (Cl. 1965-28) fore use in some manner such as in an atmosphere of hydrogen, carbon monoxide or petroleum vapors at elevated "temperatures. These mixed oxides may be supported on a carrier such as alumina, kieselguhr, Porocel, carbon, etc. The material may be further activated by the addition of small amounts up to 5% of a suitable activator such as a compound of magnesium or manganese.

The process may be carried out either in the liquid or the vapor phase. Vapor phase treatment at. 700 to 950 F. and atmospheric pressure is particularly effective.

The method of preparin the treating agent is very critical. According to the present invention, the treating agent is effectively prepared by precipitating a 2/1 iron-chromium mixture from I an aqueous solution of the chlorides by ammonium hydroxide at a pH level of 8 to 9, drying the resulting precipitate at 200 F. for about 18 hours, washing the dried precipitate with water followed by, heating at 250 F. for 64 hours and at 800 F. for two hours.

In order to test the criticality of the method of preparin the treating-agent, the oxides were also precipitated at pH levels of 7 and 10+. Each of theprecipitates were freed of the chloride by two techniques-(a) repeated washing to dissolve the ammonium-chloride followed by drying at 250 F.; and (b) drying at 200 F. and heating to 1100 F. to sublime the ammonium chlordie. In addition a portion of the washed precipitate obtained at a pH of 8-9 was additionally heated to 800 F. and another portion to 1100 F. These materials were then tested for their desulfurizing capacity by passing a benzene-thiophene mixture containing 3.0 weight percent sulfur in the vapor phaseover each of the above treat-agents. The

may be used as prepared or may be reduced befollowing results were obtained:

TABLE 1 Per cent Thiophene sulfur removed vs. 0c. Treating agent Conditions throughout Description pH NH4Clelim. F. v./v./hr. w./hr./w. 0/5 5/10 10/15 15/20 20/30 30/40 40/50 Original preparation" 8-9 wgagggg and heated to 725 1.7 1. 79' Q 41. 4:1 11 2 Second preparation.... 8-9 l zlmd heated to 725 1.7 1.79. 7 5 4 3 3 3 3..... Third preparation 8-0 Wgs5g %ahd heated to 700 1.8 1.03 28 17 15 l3 10 ll 4 --do- 8-9 Heatedtoll00 125 1.5 1.09 9 5 5 1. 7' I a a 5 do 8-9 wggggli and heated to 725 l.4- 0.88 34 '28, 24 20 15 a do 7-8 W2as5(l)1 %andheatedto 1.5 0.95 4 w a "2 7' 2 5 6 7 an 7-8' Heatedtoll00 725 1.3 0.89 5 1 1 o 2 4 8 (in 10+ wggg ei and heated to 725 1.5 1.00 6 4 2 3 3 3 a a 8-9 Heatedto1100F 725 1.1 o.o1 12 e 5 2 3 a the above data clearly show that the only maial which was eilective in removing sulfur from :benezene-thiophene mixture was the mixture oxides coprecipitated ata pH level of 8-9 and shed with water followed by heating at 250 F. r 64 hours and then to 800 F. for 2 hours. The lterial heated to 1100" F. showed poor desulrization activity at 725 F., being only 20% as 'ective as the best sample. The materials rich were washed prior to reduction showed no tter results except the sample precipitated at a I 8-9 level which removed half as much sulfur the best material.

It is also important that the mixture of oxides The above data show that coprecipitrated ferric and chromic oxides in the proportions of four parts iron to one part chromium and two parts iron to three parts chromium are poor agents for desulfurizing a benzene-thiophene blend at a temperature range of from 4'75 to 925 F. The data also show that the reduced and unreduced mixtures are equally effective.

In a second test, a gas oil fraction boiling between 400 and 700 F. containing 1.56 weight percent of sulfur was passed in the vapor phase upwardly through beds of the 2/1 and 4/1 coprecipitated iron-chromium oxides at 750 F. with the following results:

TABLE III Per Cent Reduction of Conditions 5 content Treating Agent Materials v./v.[hr. w./hr.lw 0-10 min. 48-00 min.

7 Coprecipitated Iron-Chromium Oxides:

2to1FetoCr 1.5 1.8 54 30 4tolFetoCr 1.9 2.0 3 0 Reduced Coprecipitated lro Chromium Oxides: 2tolFetoCr 1.0 1.8 51 10 M01 Fe to Cr 1.0 1.5 37 8 re coprecipitated in the ratio of about 2/1. In irder to test the criticality of these proportions, aests were made on the relative desulfurizin ability of samples of the treating agent in which :he oxides were also precipitated in the ratio of i/1 and 2/3.

A benzene-thiophene blend containing 3 weight Treating agent: Reduced 2/1 Conditions: 725 F., 1

The above results with gas oil confirm those obtained with a benzene-thiophene mixture and show the outstanding effectiveness of the 2/1 ratio for the coprecipitated oxides.

The spent mixture of iron and chromium oxides may be regenerated by heating in air to 950 F. as shown in the following data:

TABLE IV coprecipitated Fe-0r oxides. .8 v.lv.lhr., atmospheric pressure.

Feed: Benzene-thiophene blend, 3.0 wt. per cent 8.

Treating Agent Per Cent Sulfur Removed Cut Period-Min 0-6 6-12 18-24 24-36 36-48' 48-00 72-84 2/1 Reduced Fe-Cr Oxide 40. 9 40.9 11.2 6.9 Regenerated from above 41. 3 3. 3 3. 0 2. 3 2. 0

The above data show that the treating agent of the present invention may be regenerated but that while the initial activity of the regenerated ma- TABLE II Per cent 8 removed at indicated treating temperatures Treating Agent 475 F 550 F 025 F. 700 F. 725 F. 775 F. 825 F 850 F 925 F.

Fe-Cr Oxides (4/1) 21 Reduced Fe-Cr (4/1)-.- 21 Fe-Cr Oxides (2/1). 42 Reduced Fe-Cr (2/1) 43 Fe-Cr Oxides (2/3) 9 Reduced Fe-Cr (2/3)... 10 Cub-cc. 0-10 -40 00-70 -100 -150 -200 Reduced Fe-Cr (2/1) 41 ll 7 2 4 4 (Life run at 725 F., 1.8 v./v.lhr.)

Cracking was appreciably less with the Fega sate s (analyses not yet available).

ac Fe-Cr treating agent (about 2.0 v./v./hr.).

Cr mixture than with the Fe alone, based on 10 cc. is equivalent to approximately 10 min. running time using about 30 cc. of

terial is as good as the freshly prepared material, the activity falls off faster. The invention is not to containing atmosphere followed by reduction with hydrogen or carbon monoxide. Or the spent material may be regenerated in situ followed by reduction with petroleum vapors. Or the spent material may be regenerated tion or carbon monoxide.

The nature and objects of the present invention having been thus fully set forth and specific examples of the same given, what is claimed as new and useful and desired to be secured by Letters Patent is:

i=rocess for desulfurizing hydrocarbon mixtures containing sulfur which comprises passing the hydrocarbon mixture over a mixture of ferric and 250 F. for about 64 hours and then at about 806 F. for about 2 hours.

ALAN C. ABEEL, JR. HENRY J. HIBSHMAN.

REFERENCES CITED The following references are of record in thi file of this patent:

UNITED STATES PATENTS Number Name Date 2,301,802 Burk et a] Nov. 10, 1942 so 2,369,632 Byrns Feb. 13, 1945 

